This work focuses on the biochemistry and function of cell surface galactosyltransferases. Both normal (3T3) and malignant (3T12) BALB/c fibroblasts are the cell types studied. Biochemically, the enzymes are characterized starting with plasma-membrane enriched fractions. Solubilization and subsequent purification attempts are underway. The transferase inhibitor UDP-dialdehyde, a periodate oxidation product of UDP, appears to bind, specifically, to uridine-requiring transferases and does inhibit, irreversibly, N-acetyllactosamine synthesis. The UDP-dialdehyde is in use for the purification of the enzymes and to help distinguish between surface and intracellular galactosyltransferases. Functionally, the role of the enzymes in migration and recognition is being tested by allowing cells to glycosylate hyaluronic acid and chondroitin sulfate that have been derivatized to plastic substrates. The cells can be pre-loaded with labeled sugars (glucose and galactose) and the appropriate monosaccharides can be detected on the derivatized plates after they have been boiled in SDS-urea. These data indicate that some mouse fibroblasts not only are capable of the glycosylation of extracellular polysaccharides but that they carry out such glycosylation spontaneously and in the absence of added sugar-nucleotides and manganese ion.